Sizing composition of starch and a reaction product of an isocyanate with an alkylene imine and process of sizing paper therewith



United States Patent SIZING COMPOSITION OF STARCH AND A RE- ACTIONPRDDUCT OF AN ISOCYANATE WITH AN ALKYLENE IMHNE AND PROCESS OF SIZ- IN GPAPER THEREWITH Albert Goldstein, New Shrewsbury, and John W. Brook,

East Brunswick, N.J., assignors to Chemirad Corporation, East Brunswick,N.J., a corporation of Delaware No Drawing. Filed Dec. 31, 1963, Ser.No. 341,156

6 Claims. (Cl. 162-164) The present invention relates to a new andvaluable process of sizing and improving the properties of paper and thelike material and to compositions used in such sizing operations.

It is known toimprove the surface properties of paper by a treatment ofthe paper pulp and/or the finished paper sheet with a sizing agent.

Sized paper has a better surface for accepting writing or printing inks.Sizes containing casein or glue as well as rosin sizing agents are usedchiefly for sizing paper, paper board, and pulp products. Other sizingagents for paper are, for instance, the alkyl ketene dimers of theAquapel type as sold by Hercules Powder Co. and certain aliphatic fattyacids. The rosin type sizing agents and the fatty acids require fixationby means of alum and usually operation at a low pH-value. at a low pH,however, is disadvantageously affected inasmuch as its aging propertiesare impaired. Furthermore, acid reaction of the paper pulp causescorrosion of the paper making machinery. Paper made under acidicconditions is unsuitable for many purposes because of its unwantedstiffness. Therefore, many attempts have been made to provide sizingagents which work under neutral or alkaline conditions. However,heretofore, such attempts have been rather unsuccessful.

The known alkyl ketene dimer sizing agents mentioned above have beenused for sizing under neutral or alkaline conditions. Such alkyl ketenedimers, however, have the disadvantage that they require a prolongedcuring time in order to develop optimum properties. They are alsotemperature sensitive when used in a paper making system. For thisreason, they cannot be used, for instance, at a temperature of about 60C. or higher.

It is one object of the present invention to provide new and valuablesizing compositions which can be used under neutral and alkalineconditions and which are sub stantially free of the disadvantages of theknown sizing agents.

Another object of the present invention is to provide a simple andeffective process, of sizing paper by the addition of such sizingcompositions to the paper pulp before or during paper forming.

Other objects of the present'invention and advantageous features thereofwill become apparent as the description proceeds.

In principle the sizing compositions according to the present inventionare characterized by containing, as active sizing ingredients, thereaction product of a long chain aliphatic isocyanate and an alkyleneimine. The,

preferred reaction products are the reaction products of aliphaticisocyanates and especially of octadecyl isocyanate and ethylene imine.Other aliphatic isocyanates which contain between 10 carbon atoms and 20carbon atoms in their aliphatic chain may also be used, likewise otheralkylene imines which are substituted at their carbon atoms, such as theZ-methyl ethylene imine, 2-ethyl Paper sized ethylene imine,2,2-dimethyl ethylene imine, 2,3-butylene imine, and the like.

Reaction between such long chain aliphatic isocyanates and alkyleneimine may be carried out in any of the known procedures whereby reactionmay occur either in an aqueous medium or in an organic system.

It has been found to be of advantage to prepare such reaction productsin an aqueous system containing an emulsifying agent. Especiallyadvantageous emulsifiers for this purpose are, for instance, thesorbitan monooleate polyalkylene derivative sold under the trademarkTween 80 by Atlas Powder Company of Wilmington, Del, the emulsifier soldunder the trademark Gafac RE-6l0 by Antara Chemicals of New York, N.Y.;and others. By operating in this manner it is possible to obtain thedesired reaction product in the form of an aqueous emulsion which candirectly be applied to a paper pulp slurry. It is also possible to applysuch an emulsion to the finished paper sheet. If too concentrated, theemulsion of the reaction product may be applied after dilution withwater.

According to another embodiment of this invention the reaction emulsionmay be added in combination with a retention aid to the paper pulpslurry. An especially suitable retention aid is, for instance,polyethylene imine.

Other polyalkylene imines may, of course, also be used as well as otherretention aids such as the polyamideepichlorohydrin resins as they aresold for instance, under the trademark Kymene 557 by Hercules PowderCo., the retention aid sold under the trademark Reten 763 by HerculesPowder Co., the cationic starch derivative sold under the trademarkCato-8 by National Starch and Chemical Corp, and others.

According to another embodiment of the present invention the reactionproducts of alkylene imines with long chain aliphatic isocyanates, moreparticularly the reaction products of ethylene imine and octadecylisocyanate have been found to beneficially affect surface sizing ofpaper and paper board as normally practiced by tub or calender-stacksizing techniques. For this purpose emulsions of the reaction productsaccording to the present invention may be used. It is, however, alsopossible to use an aqueous dispersion of the reaction products whichpreferably is prepared from the solid reaction product by dispersing it,together with wax and starch or other surface sizing agents, in water.When using such compov sitions containing dispersions of the reactionproduct of alkylene imines with long chain aliphatic isocyanatestogether with starch and/or wax, the sizing affect of the known starchand/or wax dispersions is greatly enhanced.

Solid reaction products of alkylene imines and long chain aliphaticisocyanates as they are used for making dispersions with wax and/orstarch, are obtained by carrying out the reaction in an organic solvent,for instance, in hexane and other wherein the reaction product isinsoluble and precipitates.

The following examples serve to illustrate the present invention,without, however, limiting the same thereto.

' Example 1 range of 25 Cjto 35 C.

Upon completing the addition, the reaction mixture is adjusted to a pHof 9.0 by the addition of ammonia solution and is agitated for two hoursat about 25 C. The product mixture is then passed through a homogenizerin order to produce a uniform product.

Example 2 A solution of 200 parts of octadecyl isocyanate in 300 partsof hexane is added to a stirred solution of 30 parts of ethylene iminein 400 parts of hexane at a temperature of 25 C. The reactiontemperature is maintained at 2530 C. during the addition and for onehour after completing the addition. The reaction product is thenisolated by filtration and dried. Its melting point is 7073 C.

Example 3 Sufiicient amounts of the product of Example 1 were added toan unbleached hardwood kraft pulp of 26 S-R freeness, at a consistencyof 0.25%, to give a 0.5% additional level of the active product(octadecyl ethylene urea). Handsheets were formed at a basis weight of51 lb. (24 36500). The sheets were pressed, dried for 3 minutes at 95 C.and conditioned at 25 C. and 50% RH.

In a similar manner, sheets were produced containing 1.5% of thecompound of Example 1 and 0.5% and 1.5 of the compound of Example 1 plus0.1% of polyethylene mine.

The conditioned sheets were tested for sizing, i.e., resistance to waterpenetration, by the Cobb test (TAPPI T441m60) with water and by theflotation test (TAPPI RC-72) with 2% sodium hydroxide solution.

The results obtained were as shown below in Table I:

Cobb Sizing Flotation (sec.

Example 4 One part of the product of Example 2 and 4.1 parts of waterwere added to 37.4 parts of a starch size solution consisting of 200parts of tapioca starch, 5 parts of wax, 0.5 part of soap, 0.25 part ofsodium silicate, 1 part of sodium sulfite, and 3800 parts of water. Thisaqueous dispersion contains about 2.3 percent of the reaction product ofoctadecyl isocyanate and ethylene imine, about 4.4 percent of a tapiocastarch, and about 0.1 percent of a wax.

The resulting dispersion was applied to paper board through the waterbox on the calendar stack of a paper machine.

The resulting board surface was tested, in comparison to a standardboard treated with the unmodified size solution, for water absorbencyand wet scuff resistance.

In place of the reaction product of octadecyl isocyanate with ethyleneimine as prepared and used in the preceding examples, there may beemployed, as the one reaction component, equimolecular amounts of otherlong chain aliphatic isocyanates such as decyl isocyanate, hexadecylisocyanate, and others as well as other alkylene imines such as1,2-pr-opylene imine, 1,2-butylene imine, 2,3- butylene imine, ormixtures of ethylene imine with propylene imine and other alkyleneimines, while other Wise the procedure is the same as described in saidexamples.

We claim: I

1. A composition for sizing cellulosic sheet material comprising anaqueous dispersion having (a) from approximately 2 to 20 percent of thereaction product of a long chain aliphatic isocyanate with between 10and 20 carbon atoms in the aliphatic chain and an alkylene imineselected from the class consisting of ethylene imine, 1,2-propyleneimine, and 1,2-butylene imine, and

(b) about 4 percent of a starch.

2. The composition of claim 1 wherein the aliphatic isocyanate isoctadecyl isocyanate and the alkylene imine is ethylene imine.

3. The composition of claim 2 containing, additionally, about 0.1percent of a wax.

4. A process for sizing cellulosic fibrous material comprising adding toan aqueous cellulosic fiber dispersion an aqueous dispersion havingabout 2 to 20 percent of the reaction product of an aliphatic isocyanatewith from 10 to 20 carbon atoms in its aliphatic chain and an alkyleneimine selected from the class consisting of ethylene imine,1,2-propylene imine, and 1,2-butylene imine and about 4 percent of astarch; and forming cellulosic sheet material from the thus treateddispersion.

5. The process of claim 4 wherein the aliphatic isocyanate is octadecylisocyanate and the alkylene imine is ethylene imine.

6. The process of claim 5 wherein said dispersion contains about 2.3percent of the reaction product of octadecyl isocyanate and ethyleneimine, about 4.4 percent of a starch, and about 0.1 percent of a wax.

References Cited by the Examiner UNITED STATES PATENTS 2,341,413 2/1944Pense et a1. 2602 3,084,092 4/ 1963 Arlt 162166 FOREIGN PATENTS 681,5209/ 1939 Germany. 466,344 5 1937 Great Britain. 467,655 12/ 1951 Italy.

DONALL H. SYLVESTER, Primary Examiner.

S. LEON BASHORE, Examiner.

1. A COMPOSITION FOR SIZING CELLULOSIC SHEET MATERIAL COMPRISING ANAQUEOUS DISPERSION HAVING (A) FROM APPROXIMATELY 2 TO 20 PERCENT OF THEREACTION PRODUCT OF A LONG CHAIN ALIPHATIC ISOCYANATE WITH BETWEEN 10AND 20 CARBON ATOMS IN THE ALIPHATIC CHAIN AND AN ALKYLENE IMINESELECTED FROM THE CLASS CONSISTING OF ETHYLENE IMINE, 1,2-PROPYLENEIMINE, AND 1,2-BUTYLENE IMINE, AND (B) ABOUT 4 PERCENT OF A STARCH.
 4. APROCESS FOR SIZING CELLULOSIC FIBROUS MATERIAL COMPRISING ADDING TO ANAQUEOUS CELLULOSIC FIBER DISPERSION AN AQUEOUS DISPERSION HAVING ABOUT 2TO 20 PERCENT OF THE REACTION PRODUCT OF AN ALIPHATIC ISOCYANATE WITHFROM 10 TO 20 CARBON ATOMS IN ITS ALIPHATIC CHAIN AND AN ALKYLENE IMINESELECTED FROM THE CLASS CONSISTING OF ETHYLENE IMINE, 1,2-PROPYLENEIMINE, AND 1,2-BUTYLENE IMINE AND ABOUT 4 PERCENT OF A STARCH; ANDFORMING CELLULOSIC SHEET MATERIAL FROM THE THUS TREATED DISPERSION.